A smooth operation of the OPNV (Local Public Transit System) requires precise route data for the routes to be traveled. For example, the activation points for remotely triggering traffic signals (LSA telegrams--i.e. data communiucations) in order to preferentially switch traffic signals (LSA) have to be reproducible with a tolerance of +/-5 m. Consequently, the wireless control of traffic signals--"green wave" for buses--works properly only if the internal route transmitter generates an activation signal for the LSA telegram within a radius of +/-5 m. Conventional internal and external route transmitters generally do not meet these requirements. Only measurements relying on radio beacons with a known location would allow a sufficiently accurate determination of distances along a route. However, this method would require closely spaced radio beacons, making installation and maintenance expensive and quite complex.
Especially the activation points and the stops are therefore in general measured geodetically. However, it is quite expensive and labor-intensive to obtain such data and to input these data in the internal route transmitters of each individual vehicle. It is also disadvantageous that each change in the route system, including planned detours, requires expensive modifications because new measurements have to be performed and the data representing the changes have to be entered.